Does hydrogen with just a proton have the same spectral lines as hydrogen with a proton and a neutron?

Question

I am wondering if elements' isotopes spectral lines are identical. Does adding an extra neutron to the nucleous affect the energy levels of the electrons?

If there is a difference, what is it? in nm..

Answer 1

Not exactly the same. The extra mass in the nucleus causes a small effect in the reduced mass of the electron and so a shift in the energy levels and hence in the spectrum. This effect is used to measure cosmic deuterium abundances.

There are isotopic shifts for other elements also, but the effect is smaller because the difference in reduced mass is smaller.

Answer 2

No. The deuterium electrons are a little higher energy state because of the heavier nucleus. They're very close, and you have to use a device called a Fabry-Perot Interferometer to seperate the spectral lines from the two.

Answer 3

It does a little as the Rydberg constant depends on the reduced mass of the nucleus/electron.
Of course the nuclear spin is quite different 1H is spin 1/2 and 2H is spin 1 so NMR and other spectroscopic techniques that depend on nuclear spin will be affected.